Various Projects Find Hidden SDR Capabilities in ESP32 Microcontrollers

Developers discovered an undocumented ESP32 firmware mode that captures raw IQ samples, turning many ESP32 variants into low‑bandwidth SDRs covering 2.2–2.7 GHz and up to 6 GHz on the ESP32‑C5. Firmware can be flashed via a web page, enabling spectrum‑analysis use cases on inexpensive hardware.